When you are brushing your teeth and your toothbrush accidentally hits your uvula, causing you to throw up the food you had just eaten. This usually leads to full-on bulimia when you purposefully stick your finger in your throat and cause yourself to barf.
Trixie: Last month I was brushing my teeth and developed accidental bulimia.
Lizzie: No way! Me too! We should throw up together sometime!
Trixie: Sounds fun!